GB for Baby Huey PCB

[prasi]

Hellbender BHEL84-2nos.

 

[outriding]

Hellbender BHEL84-2nos
Outriding BHEL84-2 (one stereo set)

 

[tomlang]

Quantity 2 BH EL84 boards please. I am going to run 6GM5 (9 pin 7591A equivalent) so I will be modding board slightly.

Please post the latest EL84 version and date please, thanks.

 

[prasi]

Hellbender BHEL84-2nos
Outriding BHEL84-2 (one stereo set)
tomlang BHEL84 - 2 nos.

version.....

 

[prasi]

 

[tomlang]

Thanks. And the EL84 latest? And just so I'm not confused, there are now 6 pairs for the EL84 version?

 

[Francois G]

I believe Prasi accidentally posted the Mk2 EL34 files.

The attached files are what I have as the latest EL84 schematic and PCB (Prasi, could you confirm, please). Be aware that the schematic has not been updated for some minor improvements/mods discussed in the long BH threads.

 

[Francois G]

Quantity 2 BH EL84 boards please. I am going to run 6GM5 (9 pin 7591A equivalent) so I will be modding board slightly.

Please post the latest EL84 version and date please, thanks.

Hi Tom,

I also have plans to build a BH using 6GM5s, so I shall follow your progress with great interest. What output transformers are you planning to use? I have a pair of Sansui 1000A transformers set asside for this purpose.

 

[tomlang]

This would be my 2nd 6GM5, the first see below on AK. In that thread, is discussed how both McIntosh uses 4600 ohm primary impedance and Dave Gillespie discovered the same thing: 6GM5 (7591A) is max power at 4600 ohm primary impedance.

I am using a pair of 40W 4500 ohm primary Heyboer transformers in pentode mode at the same B+ as the Mc amp. Should be an interesting experiment.

https://audiokarma.org/forums/index...rveen-vdv-1070-uc-output-transformers.937649/

 

[Francois G]

Thanks for bringing to our attention your nice thread on AK with the Unity Coupled VdV outputs. I have missed that and shall enjoy reading it now.

 

[dch53]

Hi. I'm looking for a picture of the top of the EL84 PCB.

I purchased 2 boards in mid-2020 and I now have them assembled into a chassis. The tops of he boards with all the silk screening are no longer visible making trouble-shooting very difficult.

 

[gingertube]

dch53
See 3 posts up for EL84 PCB picture.
Not sure I interpreted your post correctly but it sounds like you have the top of the PCB against the chassis.
If that is the case you may have mounted the tube sockets on the wrong side. The tube sockets go on the back of the PCB which is the side which mounts against the chassis. Or you may have it correct and simply cant read the silk screem anymore with components mounted.
Cheers,
Ian

 

[itsikhefez]

Ian, I believe the sockets mount on the top of the PCB for the EL84 version (pin 9 is on the left, meaning it is the top of the tube socket).

Only in the latest EL34 version, the sockets were moved to the bottom of the PCB.

 

[dch53]

Thanks Ian. Itsikhefez is correct. The post 3 up shows the EL34 board.

 

[gingertube]

Post 1387 picture does show the EL84 board so I got that right.
That pic does show that the tube sockets mount on top of the board so itsikhefez got that right.
Good luck with your "set to work".
Cheers
Ian

 

[dch53]

Thanks Ian. Missed that. I need to so some measurements on the bias servo. Set it for 30mA but measuring nearly 3V from cathode to ground.

 

[prasi]

Hi,
these are the files i have from the GB. i hope they are useful.

 

[dch53]

Thanks prasi!

 

[nikon f]

Is the board still available? If so how much?

 

[dch53]

Having just completed a pair of EL84 PCBs I'd like to make a couple of suggestions:

• Move the EL84 bias pots next to the EL84 it adjusts instead of having it on the opposite side of the board adjacent to the other EL84.
• Put the silkscreen on both sides of the board. When the PCBs are placed in a chassis the lack of a silkscreen on the bottom of the board makes debugging extremely difficult and frustrating.
• If you are mounting the PCBs in a chassis, have the tubes on the appropriate side and put all the components on the other side where you can get to them. Again, this will make debugging a lot easier because you can easily hang clips on components.